Most cryosurgical systems are open-loop systems in that the cryofluid, typically Argon and/or Nitrogen, used for providing cryotherapy flows from a reservoir, e.g., a tank, under a relatively high pressure, through the one or more cryoneedles being used for providing cryotherapy, and is thereafter exhausted or purged to the surrounding environment. As such, continuous use of the system depletes the reservoir which must then be replaced. Also, substantial pressure drops across various components is an inherent characteristic of prior art open-loop systems. Therefore, it becomes necessary to ensure that the reservoir contains at least a sufficient amount of the cryofluid for completing a cryosurgical procedure without interruptions for replacing the reservoir. Accordingly, it is not uncommon to have one or more extra reservoirs on hand and ready for use if and when necessary. Often times, a partially depleted reservoir is replaced with a fully-charged tank prior to starting a procedure. As can be seen, exhausting the cryofluid from the cryoneedles after use and replacement of partially discharged reservoirs result in both waste and an increase in the cost of a cryosurgical procedure.
To the extent that closed-loop cryosurgical systems have been developed, such systems have limitations that render them unsuitable for many cryosurgical applications.
Accordingly, there exists a need for closed-loop systems for cryosurgery wherein the cryofluid is re-circulated for re-use and not deliberately exhausted after a single use, and wherein the pressure drops across the various components is minimized such that the nominal pressure throughout the closed-loop flow path is substantially less than that in prior art open-loop systems.